Battery Balancer circuit board design
Project ID:
466889
Project Type:
Fixed
Budget:
$250-$750 USD
Project Description:
The device will use an inductor connected to an oscillator to transfer energy between two adjacent batteries in series during charging and discharging to keep them at an even state of charge [see Picture 1.jpg]. Furthermore voltages of each battery must be monitored once every 10ms using a delta-sigma ADC for use in a noisy environment. Should battery voltage go above or below a preset limit, a fault pin must activate that triggers a relay which will stay triggered until voltage levels return to normal parameters. Device must go into a low power sleep mode if variance in battery voltages is within preset parameters. If any unit freezes or otherwise fails a relay must be triggered which shuts off charging or discharging.
Tri-Color LED used to display system state:
Green- Balancing
Blue- Balanced
Red blink- Low Voltage Fault
Red - High Voltage Fault
Battery voltages range from 1V to 20V
Number of batteries in series can range from 3 to 120
The current transfer requirements are up to 10A
Programmable with RS-232 pins
Circuit testing and improvements are welcome but not required. PCB layout of device should be in Gerber RS-274X and NC Drill files.
Skills required:
Electronics,
Engineering
Additional Files:
Picture 1.jpg
Public Clarification Board
1 messages
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-Balancing should occur during discharging because currently discharge must stop once the most discharged battery reaches it's lower bound. It is possible to get a little more run time if you are able to run until the pack average reaches its lower bound. This effect becomes more pronounced as
batteries age and vary in capacity.
-The device should balance just two batteries. It should be scalable by adding more devices, to accommodate up to 120 batteries. The reason the max number of batteries is given is because there is they all must be able to trigger a single fault relay.
-What must be programed is the max and min battery voltages, sleep mode conditions and any future firmware updates. I am most comfortable with the ATtiny2313 microcontroller, but it isn't essential to use.
-It should not be chemistry specific, that's why there is a large voltage range.
over 2 years ago